Machine Employing Cab Mounts and Method for Controlling Cab Mounts to Maintain Snubbing Height and Provide Mount Diagnostics

ABSTRACT

A machine employing controllable mounts and a method for controlling such mounts to maintain ideal snubbing height and provide mount diagnostics are disclosed. The controllable mount may include a housing, a pin, rheological fluid within the housing and coils provided proximate to the rheological fluid. The pin may be held in the housing with a limited degree of play by an elastomeric member and in so doing hold the pin at the ideal snubbing height. Over time the elastomeric member may degrade and begin to sag. Sensors associated with the housing may monitor this sag and if necessary energize a field across the rheological fluid or pressurize gas within the housing so as to adjust to the position of the pin back to the ideal snubbing height. The data gathered by the sensors can also be stored and used to determine the remaining serviceable life of the controllable mount and diagnose when it should be replaced.

CROSS-REFERENCE TO RELATED APPLICATION

This is a non-provisional application claiming priority under 35 USC119(e) to U.S. Provisional Patent Application Ser. No. 61/122,490 filedon Dec. 15, 2008.

TECHNICAL FIELD

The present disclosure generally relates to cab mounts and, moreparticularly, relates to machines employing cab mounts and methods forcontrolling cab mounts.

BACKGROUND

In many different heavy equipment machines, an operator cab is supportedby a frame of the machine with cab mounts. Cab mounts are available inmany different forms and configurations and generally try to isolate thecab from the undercarriage of the machine so as to limit the vibrationalimpact experienced by the operator when the machine moves or performswork. For example, with a loader traveling over rocky terrain, thechassis, undercarriage, and wheels/track of the loader may be jostledand bounced around considerably, but as the cab is not fixedly mountedto the frame, the play afforded by the cab mounts lessens the effect ofthat motion on the operator.

Such mounts can be as simple as a mechanical spring or an elastomericshock absorber offering a fixed level of vibration damping. Other typesof mounts are fluid or electro-chemical in nature. Magneto-Rheological(MR) and Electro-Rheological (ER) mounts are two examples of suchmounts. Taking a MR mount as an example, generally it includes a housingcontaining MR fluid, a structure that moves through the MR fluid, and acoil for providing a magnetic field across the MR fluid. By directingcurrent to the coils, not only is the magnetic field created through theMR fluid, but the apparent viscosity of the MR fluid is increased aswell. As the structure moves through the MR fluid, increasing theapparent viscosity of the MR fluid makes the mount more rigid.

One example of a MR mount is disclosed in U.S. Pat. No. 7,063,191. The'191 patent discloses a hydraulic mount that includes a decouplersub-assembly, a body filled with MR fluid, a pumping chamber and adiaphragm chamber. The body may be formed from a flexible, moldedelastomer, such that vibrational inputs from the engine elasticallydeform the pumping chamber to cause fluid transfer between the pumpingchamber and the diaphragm chamber through the decoupler sub-assembly forviscous damping. While somewhat effective, such a mount provides nofeedback

Another example of a MR mount is disclosed in US Patent ApplicationPublication No. 2007/0257408, published Nov. 8, 207 to Kenneth Alan St.Clair. et al. The '408 publication discloses a strut with amagneto-rheological fluid damper that includes a tubular housing filledwith magneto-rheological fluid and a piston head movable within thetubular housing along its longitudinal length.

SUMMARY OF THE DISCLOSURE

In accordance with one aspect of the disclosure, a machine is thereforedisclosed which comprises a frame, an operator cab supported by theframe, a controllable mount operatively connecting the operator cab tothe frame and including a housing, a pin mounted within the housing, anelastomeric member connecting the pin to the housing, a fluid within thehousing, a sensor operatively associated with the housing and generatinga signal indicative of relative displacement between the operator caband the frame, and an electronic controller unit operatively associatedwith the sensor and causing the fluid to bias the pin away fromengagement with the housing.

In accordance with another aspect of the disclosure a method ofcontrolling a cab mount is disclosed wherein the method comprisesconnecting a cab to a frame of a machine using the cab mount, the cabmount having a housing and a pin movable relative to and connected tothe housing by an elastomeric member, sensing a parameter indicative ofthe relative displacement between the cab and the frame, and adjusting afield across a rheological fluid within the housing until the sensedrelative displacement is equal to a desired relative displacement.

In accordance with yet another aspect of the disclosure a control systemfor controlling a mount operatively connecting an operator cab to amachine frame is disclosed, wherein the control system comprises aprocessor operatively connected to the mount, the mount including ahousing, a pin movable within the housing, a sensor adapted to generatea signal indicative of the relative displacement of the cab to thehousing, a memory adapted to store historical displacement data, analgorithm stored in the memory and executed by the processor to comparethe historical displacement data to sensed displacement data and correctactual displacement to equal desired displacement.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a machine constructed in accordance withthe teachings of this disclosure;

FIG. 2 is a sectional view of a controllable mount constructed inaccordance with the teachings of this disclosure;

FIG. 3 a chart depicting creep in an elastomeric member of thecontrollable mount during initial use, over time, and as corrected;

FIG. 4 is a schematic representation of a control system constructed inaccordance with the teachings of this disclosure;

FIGS. 5 a-d are schematic representations of alternative embodiments forsensing mount displacement;

FIG. 6 is a block diagram of an operator interface constructed inaccordance with the teachings of this disclosure;

FIG. 7 is a graph plotting frequency vs. spectral density, depictinghistorical data associated with a controllable mount, and identifyingwhen a mount should be replaced or repaired;

FIG. 8 is a graph plotting frequency vs. amplitude, and depictingstacked algorithms controlling same in accordance with the teachings ofthis disclosure;

FIGS. 9 a-e are schematic representations of different mount locationembodiments.

DETAILED DESCRIPTION

Referring now to the drawings, and with specific reference to FIG. 1, amachine constructed in accordance with the teachings of this disclosureis generally referred to by reference numeral 100. The machine 100includes a frame 102 supporting an operator cab 104. As shown, themachine 100 is depicted as a track-type tractor, but is to be understoodthat the teachings of this disclosure can be employed with equalefficacy with other heavy industry and construction machines such as,but not limited to, backhoe loaders, wheel loaders, tracked loaders,articulated trucks, off-highway trucks, excavators, motor graders,fork-lifts, skid steers, or any other machine known in the art thatincludes a cab mounted to a frame.

Referring now to FIG. 2, a cross-sectional view illustrates an exampleof one embodiment of a controllable mount 106 for use with the machine100 and method disclosed herein. As shown, the controllable mount 106may include a housing 108 that may be mounted to the frame 102 (seeFIG. 1) via a mounting flange 110. The housing 108 may include a firstchamber 112 and a second chamber 114. As will be described in furtherdetail herein, the first chamber 112 may be filled with a rheologicalfluid 116 such as a magneto-rheological (MR) fluid or anelectro-rheological (ER) fluid. The second chamber 114 may be filledwith a compressed fluid 118 such as compressed gas including compressedair.

The controllable mount 106 may also include a pin 120 that is partiallydisposed with the housing 108 and may be attached to the cab 104 at amounting end 122. The pin 120 may be attached to the housing 108 by anelastomeric member 124 that permits the pin 120 limited axial movementalong axis 126 and radial movement perpendicular to the axis 126. Theelastomeric member 124 may dampen axial as well as radial motion betweenthe pin 120 and the housing 108.

As shown, a damping plate 128 may be attached to the pin 120 and bedisposed within the rheological fluid 116 of the first chamber 112. Thedamping plate 128 may include a plurality of apertures 130 to permit therheological fluid 116 to pass through the damping plate 128. As thedamping plate 128 is moved through the rheological fluid 116, therelative motion between the housing 108 and the pin 120 is damped. Thelevel of damping may be adjusted by applying a magnetic or electricfield to the rheological fluid 116. Moreover, by changing the strengthof the magnetic or electric field, the apparent viscosity of therheological fluid 116 is proportionally changed thereby providing amechanism by which the degree of damping afforded by the controllablemount 106 can be tailored to the needs of the operator.

In order to generate the magnetic or electric field, coils 131 areprovided proximate the rheological fluid 116. More specifically, thecoils 131 may be mounted on the housing 108 laterally adjacent the firstchamber 112. Leads 132 may extend from the coils 131 for connection to acontrollable power supply 134. Alternatively, or additionally, the coils131 may be mounted on the pin 120 and/or the damping plate 128.

The pin 120 may also include a plunger 136 that separates the firstchamber 112 from the second chamber 114. The plunger 136 may include aseal 138 that seals against a shaft 140 of the housing 108. In such aconfiguration, the plunger 136 and the second chamber 114 act as a gasspring 142 for positioning the pin 120 at an ideal snubbing height 144,the importance of which will be described in further detail herein. Thepressure of the compressed fluid 118 within the gas spring 142 may beadjusted by way of a valve 146. By adjusting the pressure of thecompressed fluid 118, the biasing force of the gas spring 142 applied tothe plunger 136 is adjusted as well. A first hose or tube 148 may beconnected to the valve 146 to supply pressurized fluid 118 to the secondchamber 114. The valve 146 may also include a second hose or tube 150 toreturn the pressurized fluid 118 within the second chamber 114 to astorage tank 152, or to be vented to atmosphere.

To assist in biasing the plunger 136 toward the ideal snubbing height144, a mechanical spring 154 may also be used. The spring 154 may bedisposed about a guide extension 156 of the pin 120 and extend betweenthe guide extension 156 and a base 158 of the housing 108. The guideextension 156 may be positioned to contact the housing 108 and act as afirst end stop for the controllable mount 106.

The controllable mount 106 may also include a sensor 160 for generatinga signal indicative of the relative displacement between the cab 104 andthe frame 102. In the current embodiment, it does so by determining therelative displacement between the housing 108 and the pin 120. Thesensor 160 may include a strain gauge (not shown) disposed in a channel162 provided in the elastomeric member 124. Alternatively, the channel162 may be filled with a conductive elastomer 164 having an electricalconductivity and resistance that changes with elongation andcontraction. More specifically, the strain placed on the conductiveelastomer 164 may be correlated to the resistance exhibited by theconductive elastomer 164. Thus, as the resistance is measured, therelative displacement between the housing 108 and the pin 120 may becalculated. Leads 166 may be used to communicate data from the sensor160 to an electronic control unit 168 (see FIG. 4).

The controllable mount 106 may also include a sensor 170 to monitor thepressure of fluid 118 within the second chamber 114. The pressure sensor170 may be connected to the electronic control unit 168 as well withleads 172. In general, the pressure sensor 170 may be used to measurepressure spikes and thus wear on the elastomeric member 124. In sodoing, the remaining life and serviceability of the controllable mount106 can be calculated. In addition, failure of either sensor 160 or 170may indicate that the controllable mount 106 needs replacement orrepair.

As an alternative or addition to the sensor 160 within the elastomericmember 124, the pressure sensor 170 may also be used to determine thedisplacement of the pin 120 relative to the housing 108. Morespecifically, the displacement may be determined using the formula:

V _(n) =P _(i) *V _(i) /P _(n)

-   -   wherein:        -   V_(n) is the new volume;        -   P_(i) is the initial pressure;        -   V_(i) is the initial volume; and        -   P_(n) is the new pressure.            Initial pressure and initial volume could be initially            calibrated from a known position of the pin 120 and could            correspond to the volume and pressure of the second chamber            114. New pressure and new volume could correspond to the            displacement from the initial position. The new position may            be determined from the new volume using the formula:

D=(V _(n) −V _(i))/(π*R ²)

-   -   wherein:        -   D is the change in displacement;        -   R is the radius of the shaft 140;        -   V_(i) is again the initial volume; and        -   V_(n) is again the new volume.            Temperature compensation may also be used to increase the            accuracy of the displacement measurement. Alternatively, the            displacement may be determined through stored tables where            these calculations have already been determined.

This calculated displacement may then be used to provide feedback in acontrol algorithm executed by the electronic control unit 168controlling the mount 106. More specifically, the calculateddisplacement data may be used to adjust the current applied to the coils130 of the controllable mount 106 and hence adjust the apparentviscosity of the controllable mount 106 to provide improved performance.

In one embodiment, the apparent viscosity of the rheological fluid 116is changed in direct relation to the displacement of the mount 106.Thus, as the pin 120 moves away from the ideal snubbing height 144, morecurrent is applied to the coil and the apparent viscosity of therheological fluid 116 increases to bias the pin 120 away from engagementwith the housing 108. In so doing, the pin 120 and damping plate 128encounter greater resistance to movement and thus this feedback controlmay be used to minimize occurrences where the pin 120 reaches anendstop, also known as bottoming or topping out.

In another embodiment, statistical analysis of the data from one or moresensors 160, 170 may be used to interpret the displacement of thecontrollable mount 106 over time and adapt the control of thecontrollable mount 106 to changes in weight in the cab, i.e., the weightof different operators, their tools and accessories, and the like.Initial pressure and initial volume may be determined and calibrated atthe factory and during machine servicing.

This displacement data may also be statistically analyzed and kept forlong term storage. The historical data may include averagedisplacements, frequency domain, and power spectral density data. Thehistorical statistical displacement data may be used to determine whento replace a specific mount. For example, if the controllable mount isoperating outside of its historical average, the controllable mountwould be deemed to need replacement. Additionally, the history may betaken over the life of the controllable mount to develop a longhistorical average. The long historical average may be compared to amedium history and a short history to provide a total error or a pointby point error to look for problems in performance.

By tracking and maintaining a historical statistical average ofdisplacement, the set and creep of the elastomeric member 124 may alsobe determined. As used herein, the “set” and “creep” of the elastomericmember 124 refers to changes in the elasticity of the elastomer.Initially, the elastomer will deform predictability and return to thesame shape and strength. Over time and repetitive motion, however, theelastomer may begin to change at the molecular level so as not toexhibit the same elasticity. In the present application this can causethe elastomeric member 124 to begin to sag over time.

In graphical form, this means that as the elastomeric member 124 sags,sets, and begins to creep, the elastomeric member 124 may begin tobehave nonlinearly as shown in FIG. 3. As shown, the elastomeric member124 may initially behave in a generally linear fashion as indicated byline 174 between the end stops 176. However, over time, the elastomericmember 124 may take on a set and begin to creep as shown by line 178.

The electronic control unit 168 may be used to compensate for thischange in the material properties, as well as, minimize the effects ofcreep. For example, the electronic control unit 168 may be used toadjust the current applied to the coils 130 and thereby correct for thechange in the material properties of the elastomeric member 124, whichis shown as dotted line 180. Thus more current may be applied to thecoils 130 when negative displacement is determined and less wherepositive displacement is determined. In configurations where a pneumaticsystem is available to increase the gas pressure within the gas spring142, the increased gas pressure may be used to compensate further andbias the pin 120 toward the ideal snubbing height 144.

Referring now to FIG. 4, a schematic diagram illustrates a controlsystem 182 for a machine 100 on which the controllable mounts 106 may beused. As shown, the system 182 includes the electronic control unit 168that is in electrical communication with machine sensors 186, anoperator interface 188, and a power source 190. The electronic controlunit 168 may include a processor 192 and a computer readable media ormemory 194 for storing instructions. Machine sensors 186 may include awide variety of sensors including accelerometers, inclinometers,temperature sensors, pressure transducers, and other sensors known inthe art for use on the machine 100. The operator interfaces 188 mayinclude joysticks, pedals, switches, buttons, touch screens, keypads,and other devices known in the art for receiving operator input.

The electronic control unit 168 may also be in electrical communicationwith a plurality of controllable mounts 106 used to mount the cab 104 toa machine frame 102. Such mounts 106 may include a right frontcontrollable mount 198, a right rear controllable mount 200, a left rearcontrollable mount 202, and a left front controllable mount 204. Theright front controllable mount 198, right rear controllable mount 200,left rear controllable mount 202, and left front controllable mount 204may each include the features of controllable mount 106 described above,as well as other features of controllable mounts known in the art.

In one embodiment, the controllable mounts 106 may be identical.However, their physical positions on the machine frame 102 and cab 104may be different and known via a wiring harness 206 provided between thecontrollable mounts 106 and the electronic control unit 168. Forexample, a series of switches 208 may be coded to indicate the positionof each controllable mount 106 on the machine frame 102. If four mounts106 are used, for example, the following codes of TABLE 1 may be used:

TABLE 1 Position Switch 1 Switch 2 Cab, forward, right 0 0 Cab, forward,left 0 1 Cab, rear, right 1 0 Cab, rear, left 1 1

The harness codes may provide the switch functionality through two wiresand a ground line (not shown) being run to each mount location as partof the wiring harness 206. The switches 208 of the above table are thenprovided for in each connector by connecting a respective wire to groundto provide a 1 and left open for a 0. This may be routed through theconnector to the controllable mount 106 so that the controllable mount106 can identify its position on the machine frame 102. This positionalinformation may be used to tune and more precisely control thecontrollable mounts 106 on the machine frame 102.

In another embodiment, the controllable mounts 106 may be distinct andbe configured to receive a specific connector from the wiring harness206. Alternatively, a generic wiring harness 206 may be used and eachcontrollable mount 106 may be given its address by a technician tocommunicate its position to the electronic control unit 168.

Optionally and as shown, the controllable mounts 106 may each includethe gas spring 142 as discussed above in relation to FIG. 2. Each gasspring 142 may be pneumatically connected to a source of pressurizedgas, such as a pump 210, and a source of low pressure gas, such as thetank 152. In the depicted embodiment, the electronic control unit 168 isshown as being in communication with the pump 210, but the control neednot be electronic. For example a mechanical valve arrangement can beused. With the electronic embodiment, however, if the pressure of gaswithin the gas spring 142 of the right front controllable mount 198 isdetermined to be too low, for example, the electronic control unit 168may command the pump 210 to provide pressurized gas and command apneumatic valve (not shown) of the right front controllable mount 198 toopen and receive the pressurized gas to increase the gas pressure withinthe gas spring 142. When the pressure of the gas spring 142 issufficient, the electronic control unit 168 may close the valve and shutdown the pump 210. Alternatively, in situations where the pressure istoo high in the gas spring 142, the electronic control unit 168 may openthe valve to the tank 152 and close the valve when the pressure has beensufficiently reduced.

Accurate mount displacement measurement permits the controllable mounts106 to be maintained at or near the ideal snubbing height 144 formaximum effectiveness of the controllable mounts 106. By maintainingeach mount at their ideal snubbing height 144 throughout their usefullife, excessive loading and bottoming out/topping out of the mount 106during machine operation may be minimized or prevented. Consequently,fewer replacement parts of the cab 104 and mounts 106 may be needed overthe life of the machine 100. The present disclosure and itsaccommodating of different static loads of the cab 104 may permitdifferent systems and options to be installed at different times withouthaving to replace the mounts 106, thus providing a high degree ofmodularity and tailoring of the machine 100 to specific applicationsover the entire machine life while retaining the same mount package.

Referring now to FIGS. 5 a-d, in addition to the methods and systemsdiscussed above, controllable mount displacement measurement can beachieved with other sensors including through the use of a Hall-effectsensor 214. For example, as shown in FIG. 5 a, a permanent magnet 216may be positioned on the housing 108 of the controllable mount 106. Asensor chip 218 may be connected to the cab 104 and positioned to sensethe relative position of the magnet 216. In another embodiment (FIG. 5b), an expandable chamber 220 may house a laser 222 in one end and areceiver 224 in the other end. Each end may be attached to one of thecab 104 and the machine frame 102. As the chamber 220 expands andcontracts with the relative movement of the cab 104 and frame 102,accurate mount displacement measurement may be achieved. In anotherembodiment, a bar code reader 226 may be positioned to read a stainlesssteel or other corrosion-resistant material bar code display 228, asdepicted in FIG. 5 c. The display 228 may be attached to the frame 102and the bar code reader 226 attached to the cab 104. In yet anotherembodiment, a rotary sensor 230 with a gear 232 disposed to move up anddown a rack 234 (see FIG. 5 d) may also be used to determine thedisplacement.

In addition to diagnosing and correcting for creep or set in theelastomeric member 124, the controllable mounts 106 of the presentdisclosure also provide a mechanism by which machine feedback may beprovided to the operator. For example, the controllable mounts 106 canbe hardened and thereby selectively lower damping so as to pass more ofthe vibration and impact loads to the cab 104 from the machine frame102. As indicated above, hardening the controllable mounts 106 occurswhen an electrical current is provided to coils 131 and the apparentviscosity of the rheological fluid 116 is increased. Conversely, whenmachine feedback is not as desirable as comfort of the operator, thecontrollable mount 106 may be softened by removing or reducing thecurrent to thereby decrease damping. The level of damping may bemanually selected by the operator, programmed to change during specificintervals of machine operation, and/or based on sensor inputs asdescribed in greater detail below.

Another feature of the present disclosure is that the operator interface188 may permit the operator significant control over the controllablemounts 106. For example, as shown schematically in FIG. 6, the operatorinterface 188 may include an on/off switch 236 to enable an operator toturn the controllable mounts 106 off and thereby provide the softestride at all times. In such a situation, the controllable mounts 106would function simply as a viscous mount. Alternatively, an operator mayadjust the control algorithm via an incremented switch 238, a touchscreen 240, or a keypad 242 to scale the current flow provided by acontrol algorithm through the controllable mount 106. For example, theoperator may scale the control algorithm to fifty percent (or other) inorder to obtain a softer ride, which may result in a different dynamicrate and damping characteristics of the control system 182.

In another embodiment, the operator interface 188 may permit theoperator to have to direct control over the current being applied toeach controllable mount 106. For example, four slider bars 244 (or adifferent number if a different number of controllable mounts are used)may respectively represent the four respective mounts 106 and allow theoperator to move the slider 244 on the operator interface 188 to fit hisor her personal preferences. The operator interface 188 may be the touchscreen 240 to allow direct control, or a mouse 246 or joystick 248 maybe used to move a cursor over the screen 240 to make the desired changesto the controllable mount settings.

Further, the control of the controllable mounts 106 may be accessiblethrough the menu or operating system 250 of the machine 100. In someembodiments, control of the controllable mounts 106 may be accessibleonly to a service technician via password protection or may bepreprogrammed as part of an operator identification device 252 thatwould adjust settings to the specific operator. This may be achievedthrough the use of an RFID identification card 254, or operatorinformation stored on such items as a cell phone 256, flash drive 258,personal digital assistant 260, or other computer readable media ordevice.

The operator interface 188 may also permit the operator to input orautomatically input the geographical location of the machine 100 as wellas road and worksite material conditions. Consequently, the electroniccontrol unit 168 may adjust or implement a control algorithm to bestcompensate for the individual terrain characteristics of the worksiteand thereby provide for the best ride. For example, if a rocky worksiteis being traversed, the electronic control unit 168 may increase thecurrent flow to the coils 131 to a higher level in each controllablemount 106 in order to provide the more damping to the cab 104 andoperator. In one example, the machine 100 may operate at fifty percentof maximum current while traveling over the rocky terrain, and zeropercent over a smooth worksite.

In a different configuration, and operator may also specify the type ofmachine task being performed, in which case different control algorithms262 programmed to best damp vibrations when appropriate and allowfeedback at other times may take over. For example, if the selected taskis loading trucks from a pile of material, a loading algorithm 264 maybe selected. The loading algorithm 264 may provide the controllablemounts 106 with fifty percent (or other) maximum current while movingbetween the truck and the pile, but during bucket loading and when thebucket is raised above a predetermined height, the electronic controlunit 168 may increase the current flow to one hundred percent in orderto provide machine feedback and thus provide better operator control.

In another example, an operator may indicate that the machine 100 is amotor grader and the task to be performed is fine grading. Theelectronic control unit 168 may then cause the controllable mounts 106to be hard while the transmission of the machine 100 is in a forwardgear, and soft while in a reverse gear. During fine grading, operatorsdesire as much feedback as possible in order to more quickly completethe job within specified tolerances. Additionally, or alternatively, thecontrollable mounts 106 may be tuned to the desire of the operator forselected operational settings. For example, the operator may direct theelectronic control unit 168 to pass one hundred percent current duringfine grading, zero percent doing roading, and fifty percent during snowremoval.

In other example, a wheel loader may keep the controllable mounts 106soft during roading and moving around a worksite, but harden thecontrollable mounts 106 when the bucket is raised so that the operatorcan better feel the operation of the machine. In yet another example,the controllable mounts of a track-type tractor may be kept as soft aspossible with zero current being passed through the coils 131 while themachine 100 is being moved with the bucket and ripper up. The samemachine 100 may be programmed to pass the maximum current when either ofthose implements is performing a task.

Similarly, if the machine 100 is an excavator, when a large load isbeing placed, the controllable mounts 106 may be hardened so as toprovide the operator with valuable feedback. In contrast, when theexcavator is being moved, zero current can be passed through thecontrollable mounts 106 to provide a softer, more comfortable ride tothe operator. Commonly with excavators, the controllable mounts 106 mayalways be soft, except when transients occur during dumping, digging orother events.

The teachings of the present disclosure can also be employed fordetecting track slippage in a track-type tractor. By setting thecontrollable mounts 106 to a high current setting, the operator isprovided with increased feedback. This feedback may indicate to theoperator that track slippage is occurring. In such an event, theoperator may choose to cease operations so that maintenance can beperformed and thus minimize undercarriage wear.

The control system 182 of the present disclosure may also employ any ofthe control algorithms 262 to most effectively and expeditiously balancefeedback and comfort. In addition to the loading algorithm 264 mentionedabove, a predictive algorithm 266 may be used by the electronic controlunit 168 to control the controllable mounts 106. The controllable mounts106 may be tuned to the specific machine use and task being performed,such as dozing, ripping, grading, or excavating, or to the desiredsetting such as improved ride, noise reduction or operator comfort.Specific machine use and task may be entered by the operator asindicated above, or may be determined from the position of a blade,ripper, bucket or other implements 268 of the machine 100 as sensed byan implement position sensor 269. Alternatively, they may be inferredfrom the operator interface 188, hydraulic pressures gauges 270,worksite maps 272, global positioning system information 274, lasergrading inputs 276, topographical maps 278, inclinometers 280,determined pitch rates 282, steering signals 284, altimeters 285,articulation joint position 286, and thermometers 287. For example,shock loads may be anticipated from the position of a truck in a loadingzone and thus the controllable mount 106 may be adjusted accordingly toabsorb as much of the impact from loading as possible.

Alternatively, when the bucket of a wheel loader, tracked loader,excavator or other machine using buckets is lowered and positioned forengagement with a pile, the controllable mounts 106 may be initiallysoftened and then hardened when the hydraulic cylinder pressures exceeda predetermined threshold to provide feedback to the operator whileminimizing the impact of the bucket engaging the pile. In addition,speed of the machine 100 can be used to predict the desired settings forthe controllable mounts 106. For example, at higher speeds, as sensed bya speedometer 288, the controllable mounts 106 may be softer and thenhardened when the machine slows 100. This hardening and softening mayalso be dependent on a transmission 289 of the machine (100),specifically a gear in which the machine 100 is operating. In first geara fifty percent (or other) current may be passed through the coils 131and in a second gear forty percent may be passed. In third gear, twentyfive percent current may be passed and in fourth gear zero percent maybe passed. Harder mounts at lower speeds would provide the operator witha better feedback, while higher speeds would provide greater comfort.

The predictive algorithm 266 may also use the sensed speed of theimplement to control the controllable mounts 106. For example, when ablade is lowered the initial contact with the ground can jar theoperator. Thus, when the blade is being dropped, the controllable mounts106 may be softened in anticipation of the impact and hardened aftercontact has been made to improve feedback and control. Generally, thecontrol algorithm 262 may also be set up to control the vibrational,heave, pitch, roll and yaw modes as well. The predictive algorithm 266may also be used to predict that when an implement 268 is not in use andthe machine 100 is moving at a relatively high rate of speed, this maymean that roading is taking place and the controllable mounts 106 shouldbe adjusted for maximum comfort.

A historical algorithm 290 may also be used. More specifically, ahistogram of the performance of each controllable mount 106 may beobtained from the sensors associated with each controllable mount 106.The histogram may be used to continuously tune each individualcontrollable mount 106 to current conditions. In other words, theelectronic control unit 168 uses the sensor histories to adapt thecontrollable mount 106 to current performance, thus providing improvedperformance over time and use. For example, peak pressure and frequencymay be kept to develop a history of performance to identify when toharden and soften with decay rate. If the controllable mount 106undergoes very little movement over a past history, it can soften itselfup to avoid unnecessary harshness and wasting of energy. As more motionis seen, the controllable mount 106 can then increase damping. Forexample, if while the machine is roading, high frequency smalldisplacement vibration is sensed, the controllable mounts 106 can softenup to minimize noise, increase comfort, and save energy. When themachine 100 begins encountering rough terrain, the electronic controlunit 168 may increase current to change the damping of the controllablemount 106 to compensate for the larger low frequency displacement.

In order to prevent failure of one of the controllable mounts 106 fromcausing damage to the other controllable mounts 106 and/or other machinesystems through continued use, the sensor data collected from sensorsassociated with the controllable mount 106 may be collected and used bythe historical algorithm 290 to provide a history of operation which maythen be used to determine operating tolerances. The current sensor datamay be used to provide the power spectral density of the controllablemount 106 and determine if the controllable mount 106 should bereplaced. For example, and referring to FIG. 7, the dotted lines 292 mayrepresent the tolerances for acceptable operation for the controllablemount 106 and the solid line 294 may represent the actual running powerspectral density. A spike 296 outside of a tolerance zone 298 or anaverage error which exceeds the tolerance zone 298 may indicate that thecontrollable mount 106 should be replaced. In an alternative, thedisplacement and acceleration of the cab 104 relative to the mount 106or the exact displacement of the mount components could be used tofollow the life of the controllable mount 106 and feed the historicalalgorithm 290 to control the stiffness of the controllable mount 106.

These control algorithms 262 and the others discussed herein may beimplemented as stacked algorithms 300 as well. For example, theelectronic control unit 168 may use a default algorithm 302, an end stopalgorithm 304, and a resonant control algorithm 306. The defaultalgorithm 302 may use the controllable mount history to adjust thecurrent to performance needs. All three algorithms may be calculatedtogether and priority may be given to the algorithm that provides thehighest force control over the controllable mount 106 under the currentcircumstances. For example, and referring to FIG. 8, the machine 100 maybe roading during which the default algorithm 302 may be used to controlthe controllable mount 106. If the machine 100 moves over a pothole,that will provide an impulse to the control system 182 which if undampedis represented by line 308. Line 310 represents the effect produced bythe stacked algorithms 300 in response to the impulse. The defaultalgorithm 302 may control until the endstop algorithm 304 may then begiven priority to control the controllable mount 106. After the endstopalgorithm 304 has acted, the resonant control algorithm 306 may be givenpriority to dampen out a resonance caused by the impact with thepothole. The default algorithm 302 may resume control of thecontrollable mount 106 once the resonance has been controlled.

In addition to operator selected control and the control to provideoperator feedback, the electronic control unit 168 may be used toprovide cab 104 leveling and adjustment. Specifically, static loadadjustment and ride height adjustment may be attained by adjusting thegas spring 142 to bias the pin 120 of each mount 106 away fromengagement with the housing 108 and toward its ideal snubbing height144. This therefore avoids having the pin 120 engage the housing 108 in“topping out” or “bottoming out” fashion. The electronic control unit168 may monitor the relative displacement and adjust the gas spring 142by adding or releasing gas. If the sensors 160, 170 indicates that themount 106 is at or near the ideal snubbing height 144, no action istaken by the electronic control unit 168 to adjust the pressure withinthe gas spring 142.

This adjustment of the controllable mount 106 may be beneficial tocompensate for different sized operators who may or may not be carryingtools, food and other equipment in the cab 104. The different loads maymove the controllable mounts 106 away from the ideal snubbing height144. In some applications, the machine 100 may be operating on a slopeand thus the downside controllable mounts may bear a larger portion ofthe load. Thus, the downside controllable mounts may not be located attheir ideal snubbing heights 144. The pneumatic chamber 114 of eachmount 106 may thus be individually adjusted to return each mount 106 tothe ideal snubbing height 144.

Changes in altitude and ambient temperature may also move thecontrollable mounts 106 from their ideal snubbing heights 144. Forexample, a machine 100 that has been operating in zero degreetemperatures at sea level and then taken into the mountains and used atsix thousand feet above sea level in fifty degree temperatures may havemounts that are no longer disposed at their ideal snubbing heights 144.The present disclosure may therefore adjust for this change in altitudeand ambient temperature to return the mounts 106 to their ideal snubbingheights 144.

A mixed mount arrangement may also be used to provide reduced cost andcomplexity while providing many of the benefits associated withcontrollable mounts. For example, as shown in FIGS. 9 a-e, controllablemounts 106 may be used at some locations to provide controllability tothe cab response while using lower cost mounts to help support/attachthe cab 104 at other locations. In one embodiment (see FIG. 9 a), wherepitching of the cab 104 is desired to be controlled, two passive mounts312 may be positioned at a front 314 of the cab 104 and two controllablemounts 106 may be positioned at rear locations 316. Thus, throughselective hardening of the controllable mounts 106, the pitch and rollmotion may be controlled. The configuration may also be reversed as inFIG. 9 b with two passive mounts 312 positioned at the rear 316 of thecab 104 and two controllable mounts 106 positioned at the front 314 ofthe cab 104. As used herein, passive mounts have dampeningcharacteristics that cannot be altered during operation and include, forexample, viscous and rubber mounts.

Alternatively, a three-point system may also be possible with a singlepassive mount 312 in front 314 and two controllable mounts 106positioned at the rear 316 of the cab 104, as shown in FIG. 9 c, so thatthe structure is less expensive and easier to manufacture for plane andpositional alignment. In yet another embodiment (see FIG. 9 d), twopassive mounts 312 may be mounted near an inertial pitch axis 318 with athird controllable mount 106 being mounted away from the axis 318.

Another cab mounting arrangement may be used with machines 100 thatinclude an external roll-over protection structure 320. For example, asshown in FIG. 9 e), passive mounts 312 may be mounted between the cab104 and the frame 102 of the machine 100. One or more controllablemounts 106 may be disposed above the cab 104 and mounted between the cab104 and the external roll-over protection structure 320. In thisconfiguration, the passive mounts 312 provide noise reduction and theoverhead controllable mounts 106 may provide ride control.

INDUSTRIAL APPLICABILITY

From the foregoing, it can be seen that the teachings of this disclosurehave applicability in a variety of industrial situations, particularlywith machines to which operator cabs are mounted. Such machines mayinclude, but are not limited to, track-type tractors, wheel loaders,track loaders, excavators, motor graders, articulated trucks,off-highway trucks, skid steers, skidders, and the like. The machinesmay employ a controllable mount so as to isolate the vibrationsgenerated by the undercarriage and engine of the machine from the caband thus the operator within the cab.

In addition, by providing a mount such as that disclosed herein, theideal snubbing height of the pin within the housing can be maintained.In so doing, excessive loading and bottoming out or topping out of themount during machine operation can be minimized or eliminated. This inturn can help to extend the serviceable life of the mount. Moreover, bymonitoring the relative displacement of the pin with regard to thehousing, a diagnostic can be generated indicating when an elastomericmember of the mount, or the mount itself, should be replaced.

The teachings of the present disclosure may also be used to construct amachine that provides increased feedback to the operator. By stiffeningthe mounts, the operator will more acutely feel vibrations which canprove valuable in performing tasks, such as fine grading, plowing, orexcavating, or sensing conditions such as track slippage. Conversely,when roading the mounts can be relaxed to decrease feedback and thusprovide better operator comfort.

The present disclosure also has applicability in providing a machinemount control system wherein an operator can select a desired hardnessor feedback level through an appropriate operator interface. Such anoperator interface can also allow the operator to select the type oftask being performed and the control system can then set the mountaccordingly.

Sensors can also monitor the positions or speeds of the machine orimplements to then predict the type of task being performed. Oncepredicted, the appropriate mount settings can be used. Such a predictivealgorithm approach can not only use machine sensed parameters, bututilize global positioning satellite and other mapping technology aswell to predict the task and desired mount settings.

1. A machine, comprising: a frame; an operator cab supported by the frame; a controllable mount operatively connecting the operator cab to the frame, the controllable mount including: a housing; a pin mounted within the housing; an elastomeric member connecting the pin to the housing; a fluid within the housing; a sensor operatively associated with the housing and generating a signal indicative of relative displacement between the operator cab and the frame; an electronic controller unit operatively associated with the sensor and causing the fluid to bias the pin away from engagement with the housing.
 2. The machine of claim 1, wherein the fluid is a rheological fluid and further including coils operatively associated with the housing and adapted to create a field across the rheological fluid, the signal generated by the electronic controller unit causing the strength of the field and thus the biasing force of the rheological fluid to change.
 3. The machine of claim 2, wherein the housing includes a first chamber and a second chamber with rheological fluid in the first chamber, and further including a compressed fluid in the second chamber, the signal generated by the electronic controller unit causing the pressure of compressed fluid within the second chamber and thus the biasing force of the compressed fluid to change.
 4. The machine of claim 1, wherein the fluid assists the elastomeric member in maintaining the pin at a desired snubbing height.
 5. The machine of claim 1, further including a memory, the memory storing historical data concerning the controllable mount, the electronic controller unit adapted to compare actual sensed data about the controllable mount to the historical data and generate a signal indicating the controllable mount should be changed based on the comparison.
 6. The machine of claim 1, wherein the sensor is a strain gauge operatively associated with the elastomeric member.
 7. The machine of claim 1, wherein the sensor includes a channel within the elastomeric member filled with a conductive elastomer.
 8. The machine of claim 1, wherein the sensor is selected from the group of sensors consisting of Hall-Effect sensors, laser sensors, bar code readers, and rotary sensors.
 9. The machine of claim 4, wherein the sensor is operatively associated with the second chamber and adapted to generate a signal indicative of the pressure of the compressed fluid within the second chamber.
 10. The machine of claim 9, wherein the electronic controller unit calculates actual displacement based on the sensor signal, compares the actual displacement to an initial displacement, and the signal generated by the electronic controller unit changes the pressure within the second chamber until the actual displacement equals the initial displacement.
 11. A method of controlling a cab mount, comprising: connecting a cab to a frame of a machine using the cab mount, the cab mount having a housing and a pin movable relative to and connected to the housing by an elastomeric member; sensing a parameter indicative of the relative displacement between the cab and the frame; and adjusting a field across a rheological fluid within the housing until the sensed relative displacement is equal to a desired relative displacement.
 12. The method of claim 11, wherein the rheological fluid is in a first chamber of the housing, and adjusting the fluid involves directing more or less current through coils positioned proximate the rheological fluid so as to change the apparent viscosity of the rheological fluid.
 13. The method of claim 12, wherein the pin further includes a damping plate positioned in the rheological fluid.
 14. The method of claim 12, wherein the rheological fluid is one of a magneto-rheological fluid and an electro-rheological fluid.
 15. The method of claim 12, wherein the sensing is performed using an electronic control unit, the electronic control unit executing a control algorithm adapted to generate a diagnostic signal indicating when the elastomeric member has set and begun to creep beyond an acceptable level.
 16. The method of claim 11, further including pressurized fluid within a second chamber of the housing and adjusting the fluid involves increasing or decreasing the pressure of the pressurized fluid so as to raise or lower the pin.
 17. The method of claim 16, wherein the pin further includes a plunger and the housing further includes a seal, the pin being positioned within a middle of the seal at a desired snubbing height, the desired snubbing height being reached when the measured displacement is equal to the desired displacement.
 18. A control system for controlling a mount operatively connecting an operator cab to a frame of a machine, comprising: a processor operatively connected to the mount, the mount including a housing with a pin movable within the housing; a sensor adapted to generate a signal indicative of the relative displacement of the cab to the housing; a memory adapted to store historical displacement data; an algorithm stored in the memory and executed by the processor to compare the historical displacement data to sensed displacement data and correct actual displacement to equal desired displacement.
 19. The control system of claim 18, wherein the mount includes rheological fluid within a first chamber of the housing and coils positioned relative to the rheological fluid, and the algorithm corrects the actual displacement to be equal to the desired displacement by increasing or decreasing a level of current flowing through the coils.
 20. The control system of claim 18, wherein the mount includes a pressurized fluid within a second chamber of the housing and the algorithm corrects the actual displacement to be equal to the desired displacement by increasing or decreasing the pressure of the pressurized fluid. 